Which bushings are you referring to. There are 3 different types on the clutch pedal.
Pedal pivot bushing
Pedal Assist (overcenter) spring bushing
Pedal to Z-bar rod bushing
The pivot bushings IIRC are the same as the brake pedal bushings and should be available.
The spring bushings are not available, but you should be able to find something similar at www.Mcmaster.com, an industrial supply house.
The rod bushing is not available either. Look at Mcmaster for something similar. You may have to drill the end of the rod for a cotter pin. Many Mustang places sell a "replacement" bushing for this app that is nowhere even close, as the original was molded in place IIRC.